The present invention relates to a barking drum comprising a substantially cylindrical drum shell with an essentially horizontal axis and at least one bearing ring which surrounds an annular portion of the shell to form an interjacent gap and which is fixed relative to the drum shell by means of a plurality of fastening means fitted in the gap and spaced at equal distances around the circumference of the shell.
Bearing rings and similar devices on large rotatable drums with an essentially horizontal axis are usually secured onto the drum shell either by means of welding or by means of a screw joint. In order to be able to orient the bearing rings correctly in relation to each other, the inner diameter of the rings is usually larger than the outer diameter of the drum shell, so that an annular gap is formed between ring and shell.
When welding, several different methods of filling up this gap are used. Most frequently the gap is made so small that it can be bridged directly by weld metal. However, it is not uncommon that large drums become oval when they are at a standstill for a long period without being rotated. A disadvantage of a welded bearing ring is that it is very laborious work to alter the alignment of the ring. In addition, there are often problems with the formation of cracks in the welded joint.
When using screw joints, the ring is fixed in position on the shell by means of spacers or wedges before securing, such as in Swedish Pat. No. 187 268 (A. Ahlstrom Oy). The screw attachment is relatively expensive and, more importantly, on barking drums operating in a corrosive environment, there are often problems with corrosion between the wedge and bearing ring and between the wedge and drum shell. After a few years in service, this will cause the screw joint to loosen and it must be refastened.
In addition, the screw joint requires holes to be drilled in both the ring and the shell. Such drilling is usually done before the respective blank is bent to form the ring and the shell, which easily leads to the holes in the ring and the shell not covering each other exactly, such that one or more of the screws will have an orientation deviating from a purely radial direction.
Further, it is suggested in U.S. Pat. No. 3,783,918 (Simpson et al.) that the ring be held in position on the drum shell by pressing into the gap a plurality of rubber rods or similar elastomeric spacers, which keep the ring elastically resiliently centered on the drum and thereby considerably dampen the transmission of impact shocks from drum to the support means which carry the drum rotatably. Such an elastically resilient fastening of the ring onto the drum shell presents a problem, however, in that the drive of the barking drum cannot take place by the use of a conventional gear drive or pin gear, due to the resilient movements changing the gear teeth engagement, and destroying the lubricating oil film.
An object of the present invention is to produce an improved fixing of the bearing ring and the drum shell relative to each other. The degree of fixation should not change over a period of time, preferably not even in a corrosive environment. Nonetheless, any new alignment of the ring should only require relatively little work, and it should be possible to use a conventional gear drive or pin gear.